Mechanically-controlled power transmission device

Abstract

Mechanically controlled power transmission device comprising a rotary engine driving, through a lever and a clevis, a hydraulic slide valve which consists, in a known manner, of a rod sliding in a hole and includes blocks capable of selectively establishing communication between firstly a user device and secondly a high pressure source or an outlet. Two springs act on the slide valve in opposite directions, return the latter, in the event of a breakdown, into a neutral position which is preferably a position in which no communication is established. The device of the invention is for use in the motor car industry.

We claim: 
     
       1. Mechanically-controlled power-transmission device, comprising: a hydraulic valve capable of establishing or not establishing communications between at least one user device and either a high-pressure source or an exhaust;   an electrical rotary motor linked to the valve by linkage means, in order to transmit to the valve a linear motion; and   means for returning the valve to a predetermined safety position, these means comprising two springs acting on the valve in opposite directions, wherein the springs act independently of each other, and wherein the springs are prestressed and separated from each other in such a way that one exerts by itself the return motion when the valve travels in one direction beginning at said safety position, and the other exerts the return motion by itself when the valve travels in the other direction starting from this position.     
     
     
       2. Device according to claim 1, wherein the springs have the same stiffness value. 
     
     
       3. Device according to claim 1, wherein the springs have different stiffness values. 
     
     
       4. Device according to claim 1, wherein said predetermined safety position is not the end position of the possible course of travel of the valve. 
     
     
       5. Device according to claim 4, wherein said predetermined safety position is a position in which no communication is established. 
     
     
       6. Device according to claim 1, wherein the springs are located on either side of the valve. 
     
     
       7. Device according to claim 6, wherein each spring is interposed between two washers capable of sliding on a rod forming an extension of the valve and arranged co-linearly to the latter. 
     
     
       8. Device according to claim 7, wherein the movement of each washer is limited by a stop-motion device fitted on the rod. 
     
     
       9. Device according to claim 8, wherein the valve comprises a rod equipped with blocks sliding in a bore in a sleeve in order to seal or free holes for the establishment or elimination of said communications, and one of the stop-motion device is formed by a circlip, and the other, by an end block belonging to the valve. 
     
     
       10. Device according to claim 9, wherein one of the two washers is located so as to face one of said blocks, and has dimensions sufficient to be stopped against a corresponding end face of the sleeve in which the valve slides when the block penetrates into the bore. 
     
     
       11. Device according to claim 9, wherein the valve has a neutral position and a dead travel, the two washers are located so as to face the blocks, a clearance is defined between each of the washers and a corresponding face of the sleeve, and in the neutral position of the valve, the sum of the clearances between the washers and the corresponding faces of the sleeve is less than or equal to the dead travel of the valve. 
     
     
       12. Device according to claim 1, wherein the valve has a first and a second side and the springs are positioned on the first side of the valve. 
     
     
       13. Device according to claim 12, wherein the two springs are mounted on a single rod forming an extension of the valve on one side of the latter and arranged collinearly to this valve, each spring being interposed between two washers sliding on said rod. 
     
     
       14. Device according to claim 13, wherein the movement of each washer is limited by a stop-motion device on the rod. 
     
     
       15. Device according to claim 14, wherein, since the valve comprises a rod fitted with blocks sliding in a bore provided in a sleeve in order to seal or free holes for establishment or elimination of said communications, the stop-motion devices are formed, for one of the washers, by an end block belonging to the valve, and, for the others, by circlips provided on the rod. 
     
     
       16. Device according to claim 15, wherein the dimensions of the washers are such that, during travel of the valve, the closest of said blocks can be stopped against the corresponding end face of the sleeve in which the valve slides, and the most distant of said blocks is stopped against a wall of a body integral with the sleeve. 
     
     
       17. Device according to claim 16, wherein said wall has an opening in which the corresponding end of the rod can penetrate. 
     
     
       18. Device according to claim 16, wherein, in a neutral position of the valve, the sum of clearances between said face of the sleeve and said wall and the corresponding washers is less than or equal to a dead travel of the valve.